The present invention relates generally to the field of gas or liquid flow measurement devices used and, more particularly, to such devices which are especially useful for metering the volume of oxygen delivered to a patient from oxygen delivering equipment.
In certain medical situations it is desirable to deliver relatively high concentrations (approximately 98%) of oxygen to a patient. The period and course of administration of oxygen differs widely depending upon the precise situation, but can occur over extended periods of time, or over permanently. For medical reasons, it may be of interest to monitor the amount of oxygen which is delivered to the patient per unit time, such as minutes. For purposes of charging the patient for the use of the equipment, it is useful to meter the accumulative amount of oxygen delivered to the patient.
Due to the relatively low pressures and flow rates encountered in such situations (ranging usually from 1-10 p.s.i. and from 0.5-10 liters/min.), it is important for purposes of measurement accuracy to minimize any interruption of flow caused by the measuring device. Also, due to the fact that oxygen is highly explosive, the means by which measurement of flow volume is accomplished must be restricted to one which will not present a significant risk from this hazard.